I 'believe' that the ECU can only change timing in this way if there is/are
knock sensor[s] and it's connected to them and set up to do this.

Mike

----- Original Message -----
From: Jennifer <ncc876@YAHOO.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, June 14, 2001 1:14 PM
Subject: Re: Octane

> At 9:33 AM -0600 6/14/01, Richard A. Jones rearranged electrons to say:
>
> >>>In Texas and New Mexico ALL of the regular gas
> >>>was 86 octane.  Anyone know why this is so?
> >
> >Regular is 86 here in Colorado.  I've been told that
> >the refiners lower it because of the altitude.  I have
> >noticed 87 at lower altitude places....
>
> Gasoline has different octane ratings because the different levels
> inhibit premature detonation before the spark plug fires (knocking).
> Since this can damage the engine, it is important to put the proper
> octane gas in your car (see the owner's manual for details)
>
> At higher altitudes, there is not as much oxygen in the air
> (explaining why people get winded more easily in places like
> Colorado) and thus it is harder to ignite gasoline. For that reason,
> it is not necessary to use as much octane in your motor fuel. Most
> manuals are written to assume you'll use your vehicle at altitudes
> around sea level because most inhabited areas of the US are pretty
> close to it.
>
> Feed your car the wrong octane level, and chances are the ECU will
> inhibit your ignition timing to prevent knocking and cylinder wall
> damage. A friend of mine came to me asking why his Camaro "isn't
> making Mustangs shrink as fast as usual" and I asked him some
> questions, including what gas he was using. It turns out he was using
> 89 instead of the recommended 91 -- and his own engine was slowing
> down to prevent expensive damage later on. I think this was the
> 8-cylinder engine...
>
> Not enough time has passed to know if switching back to 91 octane
> solved the problem, but I suspect that it will.
> --
>
> -----
>
> Jennifer - ncc876@yahoo.com
> ... knee-deep in the hoopla ...
>
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